(1) Field of the Invention
The present invention relates to a torque beam assembly for a vehicle suspension system. In particular, the present invention relates to a vehicle suspension system torque beam having a resilient pivot bushing clamp at one end and a flexible axle seat assembly at its other end. The bushing clamp is clamped over a pivot bushing having recesses in its end walls that enable operative movement of the torque beam on the bushing while reducing the torsional stress on the torque beam caused by the movement. The axle seat assembly provides a flexible connection between the vehicle axle and the torque beam without the use of additional bushings to connect the axle seat to the torque beam.
(2) Description of the Related Art
Suspension systems of the type provided by the present invention are connected at opposite sides of a vehicle to the underside of the vehicle chassis. The systems connect an axle of the vehicle to the chassis. The suspension systems on opposite sides of the vehicle are in most cases identical. One of the pair of suspension systems comprises a hanger member, a torque beam, an axle seat, and an air spring.
The hanger member is connected to the underside of the vehicle chassis and depends downward from the chassis. The hanger member supports a pivot bushing that pivotally mounts the torque beam to the hanger member.
A first end of the torque beam is connected to the pivot bushing, thereby providing the pivoting connection between the torque beam and the hanger member. The connection to the bushing also permits limited torsional twisting of the torque beam relative to the hanger member. The second end of the torque beam is connected to the axle seat that supports the vehicle axle.
The axle seat is commonly connected to the second end of the torque beam by a pair of bushings that permit limited torsional twisting of the axle seat relative to the torque beam. The air spring is generally provided between the axle seat and the vehicle chassis. A shock absorber is also generally provided between the chassis and the axle seat.
The bushing connections between the torque beam and the hanger member, and between the torque beam and the axle seat supporting the vehicle axle, enable limited movement of the vehicle axle relative to the torque beam without imparting sufficient torsional stress on the torque beam to damage the beam.
Torque beams of suspension systems of the type described above are generally pivotally connected to the hanger members by a pivot bushing assembly. Prior art torque beams are often provided with a hole through their first end, opposite their second end connected to the axle seat. The bushing assembly is press fit into the hole to provide a secure friction connection between the exterior of the bushing assembly and the torque beam. The first end of the torque beam, along with the inserted bushing, is then positioned between the side walls of the hanger member. A bolt is inserted through aligned holes in one side wall of the hanger member, through the bushing center, and in the opposite side wall of the hanger member. The bolt is then secured by a nut to pivotally mount the torque beam to the hanger member by the pivot bushing.
When the torque beam requires replacement or repair, or when the pivot bushing requires replacement due to wear, the torque beam must first be removed from the hanger member and the bushing removed from the torque beam. This requires removing the nut and bolt fastener connecting the bushing assembly to the hanger and removing the torque beam together with the bushing from the hanger. The bushing assembly is then removed from the hole extending through the first end of the torque beam by pressing the bushing completely through the hole. This procedure is time consuming and often damages the bushing as it is removed from the torque beam, preventing the bushing from being reused when the suspension system is reassembled.
The procedure for removing the bushings that mount the axle seat to the second end of the torque beam is often substantially the same as the procedure for removing the bushing assembly at the first end of the torque beam. Once nut and bolt fasteners extending through the opposite sides of the axle seat and through the centers of the bushing assemblies are removed, the axle seat is removed from the second end of the torque beam. The bushings are then removed from holes extending through the second end of the torque beam by being pressed through the holes. This procedure is also time consuming and often damages the bushing assemblies as they are removed, preventing their reuse when the suspension system is reassembled. The periodic replacement of the bushing assemblies connecting the first end of the torque beam to the hanger member, and connecting the axle seat assembly to the second end of the torque beam, and the time spent to make these replacements, represent a significant portion of the maintenance costs for vehicle suspension systems of this type.
The torque beam assembly of the present invention reduces the costs involved in maintaining a vehicle suspension system by providing a unique torque beam construction that reduces the time required to remove a pivot bushing assembly connecting the torque beam to a hanger member from the first end of the torque beam without damaging the bushing assembly. The torque beam also reduces the number of bushings required for a vehicle suspension assembly by providing a unique axle seat assembly that is connected directly to the second end of the torque beam without the use of additional bushings. The torque beam assembly is also provided with an improved pivot bushing construction that facilitates the torsional twisting of the torque beam during normal suspension system operation while reducing torsional stresses on the torque beam. The torque beam assembly requires only the single pivot bushing assembly connecting the torque beam to a hanger member, yet functions in a manner equivalent to prior art suspension systems employing torque beams with second and third bushing assemblies connecting the axle seat assembly to the second end of the torque beam.
It is therefore an object of the present invention to provide an improved torque beam assembly for vehicle suspension systems which provides an improved pivot bushing assembly that reduces torsional twisting stress in the torque beam during operation, a pivot bushing clamp at a first end of the torque beam that enables removing the pivot bushing from the torque beam in a reduced amount of time and without damaging the bushing, and an improved axle seat assembly connected at the second end of the torque beam that is capable of flexing relative to the second end of the torque beam during normal suspension system operation yet uses no additional bushing assemblies to connect the axle seat to the torque beam.